1. Field of the Invention
The present invention relates to a tamper-indicating tape for use with a container to indicate opening of the container.
2. Discussion of the Art
U.S. Pat. No. 4,876,123 discloses a tamper-indicating tape for securing a first container part to a second container part to enclose an opening in the container. The tamper-indicating tape includes a light-transmissive monolayer film having opposing first and second major surfaces.
First colored indicia are printed on the first major surface of the film and second colored indicia are printed on the second major surface of said film. The first and second indicia have contrasting colors. Adhesive means is provided for adhering the film to the first and the second container parts with a bond strength greater than the force required to split the film. The adhesive means is coated on the first major surface of the film opposite the second indicia with a color substantially identical with the color of the second indicia so that the second indicia are obscured when viewed against the adhesive means through the second major surface of the film.
When the film is split, such as if the tape is attempted to be removed from the container, it becomes opaque so that the first indicia are obscured when viewed through the split film, but the second indicia are perceptible over the split opaque film to indicate separation of the first and second container parts.
In order to prepare the tamper-indicating tape, it is necessary to print first colored indicia and second colored indicia in such a manner so as to obscure the indicia in the absence of tampering. This requirement is difficult to fulfill, because perfect registration and good color matching between the ink of the indicia and the dye or pigment of the adhesive is required. Accordingly, it would be desirable to find a way to utilize the film disclosed in U.S. Pat. No. 4,876,123 without having to resort to a printing pattern that requires skillful alignment of first colored indicia and second colored indicia and good matching of the ink of the indicia with the dye or pigment of the adhesive.